Objective lens and scanning device using such an objective lens
AssigneeKoninklijke Philips Electronics N.V.
InventorsBernardus Hendrikus Hendriks, Teunis Tukker
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Abstract
The invention relates to an objective lens and an optical device for scanning different information carriers having different cover layer thicknesses, with different numerical apertures. The objective lens (10, 20) comprises at least an annular part (101, 201) having a first numerical aperture and a central part (102, 203) having a second numerical aperture. The second numerical aperture is higher than the first numerical aperture.
Claims10
An optical scanning device for scanning at least a first type of information carrier (11) having a first information layer (111) and a first transparent layer (112) of a first thickness and a second type of information carrier (12, 411) having a second information layer (121, 412) and a second transparent layer (122, 413) of a second thickness greater than the first thickness, said optical scanning device comprising means (401, 402) for generating at least a first and a second radiation beam (403, 404), and an objective lens (10, 20, 408) comprising at least an annular part (101, 201) having a first numerical aperture and a central part (102, 203) having a second numerical aperture higher than the first numerical aperture, wherein the first information layer is intended to be scanned by the first radiation beam through the central part of the objective lens and the first transparent layer, and the second information layer is intended to be scanned by the second radiation beam through the annular part of the objective lens and the second transparent layer.
An optical scanning device for scanning at least a first type of information carrier having a first information layer and a first transparent layer of a first thickness and a second type of information carrier having a second information layer and a second transparent layer of a second thickness greater than the first thickness, said optical scanning device comprising means for generating at least a first and a second radiation beam, and a lens assembly comprising a first lens (30) with an annular part (301) having a first numerical aperture and a central part (302), and a second lens (31), the second lens and the central part of the first lens forming a dual-element objective lens having a second numerical aperture higher than the first numerical aperture, wherein the first information layer is intended to be scanned by the first radiation beam through the dual-element objective lens and the first transparent layer, and the second information layer is intended to be scanned by the second radiation beam through the annular part of the first lens and the second transparent layer.
An objective lens (10, 20) comprising at least an annular part (101, 201) having a first numerical aperture and a central part (102, 203) having a second numerical aperture, wherein the second numerical aperture is higher than the first numerical aperture.
A lens assembly comprising a first lens (30) with an annular part (301) having a first numerical aperture and a central part (302), and a second lens (31), the second lens and the central part of the first lens forming a dual-element objective lens having a second numerical aperture, wherein the second numerical aperture is higher than the first numerical aperture.
Dependencies are inferred from the claim text.